:root {
  --bg-main: #fafbfc;
  --grid-line: #c4d7ed;
  --text-dark: #253085;
  --muted: #5d6d84;
  --black-stone: #bd9368;
  --black-stone-light: #ddb368;
  --white-stone: #465bcf;
  --white-stone-light: #8da4f1;
  --highlight: #fdf388;
  --panel-border: #d7e2ee;
  --thinking-bg: #eef5ff;
  --danger: #d96d52;
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html,
body {
  min-height: 100%;
}

body {
  background: var(--bg-main);
  color: var(--text-dark);
  font-family: "Segoe UI", "PingFang SC", "Noto Sans SC", sans-serif;
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 16px;
}

.game-container {
  width: min(760px, 100%);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 18px;
}

.page-header {
  width: 100%;
  text-align: center;
  display: grid;
  gap: 8px;
}

.eyebrow {
  font-size: 0.75rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--black-stone);
}

.page-header h1 {
  font-size: clamp(1.45rem, 2.8vw, 2.1rem);
  font-weight: 700;
}

.intro-copy {
  font-size: 0.96rem;
  color: var(--muted);
}

.rules-panel {
  max-width: 680px;
  margin: 0 auto;
  text-align: left;
  border: 1px solid var(--panel-border);
  border-radius: 12px;
  padding: 10px 12px;
  background: #fff;
}

.rules-panel summary {
  cursor: pointer;
  font-weight: 600;
}

.rules-panel p {
  margin-top: 8px;
  line-height: 1.65;
  color: var(--muted);
}

.game-panel {
  width: 100%;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 14px;
}

.status-bar {
  width: 100%;
  min-height: 52px;
  display: grid;
  gap: 8px;
  justify-items: center;
  text-align: center;
}

.status-bar.is-thinking {
  background: var(--thinking-bg);
  border-radius: 12px;
  padding: 10px 12px;
  animation: pulse 1.2s ease-in-out infinite;
}

.status-main {
  display: grid;
  gap: 4px;
}

#statusText {
  font-size: 1rem;
  font-weight: 700;
}

#statusSubtext {
  font-size: 0.9rem;
  color: var(--muted);
}

.status-meta {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 14px;
  font-size: 0.88rem;
  color: var(--muted);
}

.board-row {
  display: flex;
  gap: 8px;
  justify-content: center;
  align-items: flex-start;
}

.affine-grid {
  display: grid;
  grid-template-columns: repeat(5, 56px);
  grid-template-rows: repeat(5, 56px);
  gap: 2px;
  background: var(--grid-line);
  border: 2px solid var(--grid-line);
}

.infinite-column {
  display: flex;
  flex-direction: column-reverse;
  gap: 2px;
}

.infinite-row {
  display: flex;
  align-items: center;
  gap: 6px;
  height: 56px;
}

.slope-label {
  width: 48px;
  text-align: right;
  font-size: 0.8rem;
  color: var(--black-stone);
  letter-spacing: 0.3px;
}

.board-cell,
.infinite-cell {
  position: relative;
  background: #fff;
  border: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: background-color 0.12s ease;
  touch-action: manipulation;
}

.board-cell {
  width: 56px;
  height: 56px;
}

.infinite-cell {
  width: 56px;
  height: 56px;
  border: 1px solid var(--grid-line);
}

.board-cell:hover,
.board-cell.is-clickable,
.infinite-cell:hover,
.infinite-cell.is-clickable {
  background: #eaf1fb;
}

.board-cell:disabled,
.infinite-cell:disabled {
  cursor: default;
}

.board-cell.is-last-move,
.infinite-cell.is-last-move {
  background: #fff2d5;
}

.board-cell.is-winning-line,
.infinite-cell.is-winning-line {
  background: #fff7bd;
  box-shadow: inset 0 0 0 2px #d9b24f;
}

.board-cell.is-winning-line.is-last-move,
.infinite-cell.is-winning-line.is-last-move {
  background: #ffe9a0;
}

.piece {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.08);
}

.piece.black {
  background: linear-gradient(180deg, var(--black-stone-light), var(--black-stone));
}

.piece.white {
  background: linear-gradient(180deg, var(--white-stone-light), var(--white-stone));
}

.index-label {
  position: absolute;
  right: 4px;
  bottom: 3px;
  font-size: 0.68rem;
  color: rgba(37, 48, 133, 0.55);
}

.toolbar {
  width: 100%;
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  align-items: center;
  gap: 10px;
}

.toolbar-button {
  appearance: none;
  border: 1px solid var(--grid-line);
  border-radius: 999px;
  background: #fff;
  color: var(--text-dark);
  padding: 9px 16px;
  font: inherit;
  font-weight: 600;
  cursor: pointer;
}

.toolbar-button-primary {
  border-color: var(--black-stone);
  background: #fffaf1;
}

.toolbar-button:disabled {
  opacity: 0.5;
  cursor: default;
}

.toolbar-toggle {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 0.92rem;
  color: var(--muted);
}

.loading-overlay {
  position: fixed;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
  background: rgba(250, 251, 252, 0.72);
  backdrop-filter: blur(4px);
}

.loading-overlay.hidden {
  display: none;
}

.loading-card {
  width: min(320px, 100%);
  padding: 22px 18px;
  border-radius: 16px;
  border: 1px solid var(--panel-border);
  background: #fff;
  text-align: center;
}

.spinner {
  width: 38px;
  height: 38px;
  margin: 0 auto 12px;
  border-radius: 50%;
  border: 4px solid #dbe6f4;
  border-top-color: var(--white-stone);
  animation: spin 1s linear infinite;
}

#loadingTitle {
  font-weight: 700;
}

#loadingMessage {
  margin-top: 8px;
  line-height: 1.6;
  color: var(--muted);
}

@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}

@keyframes pulse {
  0%, 100% {
    box-shadow: 0 0 0 0 rgba(70, 91, 207, 0.05);
  }
  50% {
    box-shadow: 0 0 0 8px rgba(70, 91, 207, 0.08);
  }
}

@media (max-width: 640px) {
  body {
    align-items: flex-start;
  }

  .game-container {
    gap: 14px;
  }

  .board-row {
    flex-direction: column;
    align-items: center;
  }

  .infinite-column {
    flex-direction: row;
    flex-wrap: wrap;
    justify-content: center;
    gap: 8px;
  }

  .infinite-row {
    flex-direction: column;
    height: auto;
    gap: 4px;
  }

  .slope-label {
    width: auto;
    text-align: center;
    font-size: 0.74rem;
  }
}